Doctors can diagnose fatty liver disease, now called metabolic dysfunction-associated steatotic liver disease (MASLD), using blood tests that measure serum liver enzyme levels. Elevated enzyme levels may indicate inflammation and disease in the liver.
Instead of nonalcoholic fatty liver disease (NAFLD), experts now call it metabolic dysfunction-associated steatotic liver disease (MASLD). It’s a condition marked by a buildup of fat in the liver. It is the most common cause of liver disease in the United States and doesn’t typically cause symptoms until it’s advanced.
Your doctor may regularly test your liver enzymes if you have certain conditions related to this type of liver damage, including obesity, metabolic syndrome, and type 2 diabetes.
Here’s more about what blood tests doctors use to diagnose and monitor MASLD, how they’re performed, and what the results mean.
Blood tests for MASLD measure key enzymes and proteins in the blood. Elevated levels of enzymes may indicate inflammation and damage in the liver. The tests to evaluate liver function are part of a broader blood test called liver function tests.
The specific tests for diagnosing MASLD include:
- Alanine transaminase (ALT) test: The ALT blood test measures the level of the ALT enzyme, which helps turn proteins into energy for the liver cells, in your blood.
- International normalized ratio (INR) test: Also called the prothrombin time (PT) test, this blood test assesses liver health by measuring the time it takes your blood to clot. A high INR result may mean your liver isn’t functioning properly.
- Albumin test: The serum albumin test measures the amount of protein in your blood.
- Complete blood count (CBC): A CBC test is another marker of liver health, as a low platelet count may indicate cirrhosis.
- FibroSURE test: A fibroSURE test measures six markers of liver function and assigns a score to indicate how well your liver functions.
Typical ALT levels fall between 0 and 35 units per liter (IU/L), though each lab may have a slightly different range. A result outside this range doesn’t mean you have MASLD, but it does warrant more investigation via ultrasound (FibroScan, a type of liver ultrasound), MRI, and CT scan.
Your doctor may also use the results from your ALT — along with your age and platelet count — to calculate your Fibrosis-4 Index (FIB-4). The FIB-4 score helps indicate how advanced scarring on your liver, known as liver fibrosis, may be. A score over 2.67 in people with MASLD helps predict advanced fibrosis up to 80% of the time.
To have a blood test done, you will go to a laboratory at a doctor’s office or local hospital. Liver function tests need to be done on an empty stomach, so follow the doctor’s instructions for when to start fasting before your test.
The phlebotomist — a healthcare professional who draws blood — will take you to a private area, ask you to roll up your sleeve, and then extend one arm. After that, the phlebotomist will tie a tourniquet above your elbow and ask you to make a fist to help locate a vein. Before inserting the needle to collect the blood sample, the phlebotomist will clean the area using an alcohol wipe.
There is currently no specific medication to cure MASLD. Instead, doctors recommend diet changes and exercise to
There is a direct relation between the outlook for people with MASLD and their level of liver scarring. People with minimal damage may respond well to lifestyle changes.
Those with advanced scarring may need medications to treat complications of cirrhosis, such as Resmetirom (Rezdiffra), which the
Other treatment options may include surgery or a liver transplant for liver failure.
What ALT level may mean you have fatty liver disease?
An ALT level over 30 IU/L in men and 20 IU/L in women, when combined with fatty liver on imaging tests, indicates fatty liver disease, which is now called metabolic dysfunction-associated steatotic liver disease (MASLD). That said, a level over the normal range alone doesn’t always mean you have the condition.
What is the normal range for fatty liver tests?
Healthy ALT levels in men are less than or equal to 30 IU/L. Healthy ALT levels in women are less than or equal to 20 IU/L.
What are the three signs of fatty liver disease?
A person with MASLD may not always have symptoms. Possible signs of advancing disease include unexplained weight loss, weakness or tiredness, and pain in the upper right quadrant of the abdomen.
Doctors may use several blood tests to help them assess liver function and diagnose MASLD. If these tests are abnormal, a doctor will likely recommend additional testing via ultrasound or other imaging to evaluate liver damage. After that, the doctor may follow up with blood testing and ultrasounds every 6 to 12 months to track the disease.
With conservative treatment, like gradual weight loss and healthy lifestyle habits, it’s possible to manage MASLD and keep it from progressing.